1. Chemical Reaction Engineering (CRE) is the field that studies the rates and mechanisms of chemical reactions and the design of the reactors in which they take place. Lecture 10

2. Today’s lecture Definition of Selectivety Instantaneous S D / U = r D /r U Overall = F D /F U Semibatch Reactors 2

3. Selectivity in Multiple Reactions SelectivityYield Instantaneous S D/U = r D /r U Overall Ŝ D/U = F D /F U 3 Keep C A high and C B low.

4. Semibatch reactors Semi Batch reactors can be very effective in maximizing selectivity in liquid phase reactions. The reactant that starts in the reactor is always the limiting reactant. 4

5. Semibatch reactors A + B → C + D Semibatch reactors 5 A B, v 0 Initial V Liquid level and volume increase

6. Semibatch reactors 6 Mass Balance:

7. Semibatch 7 1)Mole balances: Species A: in – out + gen = acc

8. Semibatch 8 1)Mole balances: Species B:

9. Semibatch 9

10. 2) Rate Law: 3) Stoichiometry: 4) Parameters: 10

11. example: A + B → C + D + CO 2 A B, v 0 CO 2 Semibatch Example 1a) Mole balances: 11

12. 1 b) Mass balances: Semibatch Example 2) Rate Law: 12

13. 3) Stoich: Semibatch Example 4) Parameters: 13

14. Polymath Screenshots: 14

15. Semi Batch Reactors Three Forms of the Mole Balance applied to Semi Batch Reactors: 1.Molar Basis 2.Concentration Basis 3.Conversion 15

16. Consider the following elementary reaction: A+B  C+D -r A =kC A C B The combined Mole Balance, Rate Law, and Stoichiometry may be written in terms of number of moles, conversion, and/or concentration: ConversionConcentrationNo. of Moles 16

17. Polymath Equations: 17

18. Equilibrium Conversion in Semibatch Reactors with Reversible Reactions Everything is the same as for the irreversible case, except for the rate law: Consider the following reaction: A+B  C+D 18

19. Equilibrium Conversion in Semibatch Reactors with Reversible Reactions Where: At equilibrium, then 19 X e changes with time.

20. End of Lecture 10 20